PCOS is a clinical condition characterized by the presence of two or more of these features: chronic oligo-ovulation or anovulation, androgen excess and polycystic ovaries.1 As the most common cause of anovulatory infertility, PCOS affects 6-8% childbearing-aged women.2,3 Additionally, PCOS is associated with important endocrine-metabolic derangements and a broad range of adverse sequelae, including dyslipidemia, atherosclerosis, insulin resistance and type 2 diabetes.4-6 Insulin resistance is present in perhaps 50% of women with PCOS.7 Among women with impaired glucose tolerance (IGT) and diabetes mellitus, about 20% were recognized at younger age to have PCOS.8-10 
The pathogenesis of PCOS is not fully understood. Heritable tendencies have long been recognized, but complex interactions exist between genetic and environmental factors. Association studies have been conducted on at least 70 candidate genes, principally related to reproductive hormones, insulin resistance, and chronic inflammation, e.g., follicle stimulating hormone receptor(FSHR), cytochrome P450, family 11A (CYP11A), insulin receptor (INSR) and interleukin 6 (IL-6)11-15; however, none correlates consistently with PCOS.16 